Planar inductors with a flat coil carry layer which carries dispersed flat coils in a plane are well known (for example, see Patent Document 1).
The planar inductor is configured as a mouse pad. Built into the mouse pad is a power transmission system which transmits, without contact, power supplied from a plug to a cordless mouse. The power transmission system consists of a frequency conversion circuit which converts the power at commercial frequency supplied from the plug into the power at a desired frequency, and multiple planar spiral coils which are provided within the mouse pad. The planar spiral coils are laid on the upper surface of a soft magnetic ferrite plate and connected so that the mutually adjacent planar spiral coils each face in the opposite direction to correspond to the direction of the flux at a given time.                Patent Document 1: Unexamined Patent Publication (Kokai) No. H11-95922        